Gas exchange Mrs. Jackie Maldonado

Respiratory system Composed Trachea- branches into two bronchi Bronchi- branches into many bronchioles Bronchioles- end up in a sac called alveoli lungs

Features of alveoli for gas exchange Large surface area provided by millions of alveoli in the lung Short distance for gases to travel, due to fact that the walls of the alveolus and the blood capillary are made on one cell layer each. The moist surfaces of alveoli allow the gases to dissolve in water and then pass in and out between the alveoli and the capillaries

Features of alveoli for gas exchange Network of capillaries surrounding the alveolus, ensuring constant blood flow Concentration gradient of gases between the alveoli and the capillaries is very high which allows fast diffusion of gases

Concentration of gases an explanation Oxygen concentration is high in the alveoli which contain oxygen from the atmosphere while in the blood is low (used in respiration) Carbon dioxide is high in the blood due to respiration and low in the alveoli. Only 4% of oxygen is used in each breath from 20% inhale

Features of alveoli for gas exchange Hemoglobin in the red blood cells has high affinity to oxygen and so it combines with a great speed RBC are large in size compared with the diameter of the capillaries allowing efficient loading and unloading of gases

The need for a ventilation system

Ventilation system Needed to maintain a high concentration of oxygen in the alveoli and low CO2. Produced by changes in pressure in the chest cavity carry by Diaphragm Intercostals muscles

Mechanism of ventilation Inspiration or inhale Diaphragm contracts and flattens Intercostal muscles also contract and pull the ribcage outward and forward The chest cavity become larger and the pressure smaller The air rushes from the atmosphere into the lungs, moving from higher to lower pressure

Mechanism of ventilation Exhale or expiration The diaphragm relaxes, becoming dome shaped, The intercostal muscles relax Ribs move downward and backward Chest cavity decrease in volume and the pressure increases. Air is pushed out of the lungs into the atmosphere moving from higher to lower pressure

What is the difference between breathing and cell respiration? Cell respiration Process that occurs inside the cell which results in the production of ATP Breathing Mechanical process that causes ventilation maintaining high O2 and low CO2 in the blood

How does exercise improve the functioning of the heart and lungs? Strengthens and enlarges muscles Heart rate increases sending more blood to the working muscles, increasing cardiac output Cardiac output= stroke volume X heart rate Stroke volume= volume of blood ejected by the ventricles in one beat.

How does exercise improve the functioning of the heart and lungs? After training the heart rate would not increase much because the heart is stronger and the stroke volume is more Before training our breathing rate increases as well as our tidal volume Tidal volume- volume of inhale air in each breath In athletes they increase cardiac output by increasing stroke vl. and not heart rate and increase their ventilation by increasing their tidal vl and not breathing rate

Why does breathing rate increase during exercise? To provide more O2 and glucose to the muscles for the process of respiration and to remove carbon dioxide which increase acidity of blood

How does breathing rate increase with exercise? Respiration rate in muscles increases as well as CO2 levels and pH decreases pH decreases affect chemosensors located at the aorta and carotid arteries. Chemosensors send messages to the respiratory centers in the brain stem which in turn send messages to the breathing apparatus. These muscles contract and relax faster increasing breathing rate.

Health problems associated with gas exchange Lung cancer Tuberculosis Asthma Emphysema

Asthma Results from allergy to chemicals (allergens) which irritate trachea and bronchi Cause constriction of bronchioles thus small tidal volume Could lead to dead Increases by seasons

Asthma

Emphysema Caused by smoking Substances in smoke stop the beating of cilia so that air particles enters to the air passages Results in coughing resulting in walls of the alveoli breaking apart Less surface area less gas exchange Could also results in dead